Novel intumescent composition containing an aromatic amine sulfate

ABSTRACT

1. AN INTUMESCENT COMPOSITION COMPRISING AS THE INTUMESCENT AGENT A MIXTURE OF (A) ONE MOLAR PROPORTION OF A SULFATE OF AN AROMATIC AMINE OF THE GROUP CON SISTING OF P-NITROANILINE, O-NITROANILINE, M-NITROANILINE, 3AMINO-1-NITRONAPTHALENE, 4-AMINO-4&#39;&#39;-NITRO-BPHENYL, 1,5DIAMINO 4,8-DINITRONAPTHALENE, 2-AMINO-7-NITROFLUORENE, 4-AMINO-2-NITROFURAN, 5-NITROISATOIC ANHYDRIDE, AND 4NITROACETANILIDE AND (B) ABOUT 1-5 MOLAR PROPORTIONS OF A BORON COMPOUND OF THE GROUP CONSISTING OF BORIC ACID, AN ORGANOBORIC ACID, AN ORGANOBORATE, AND AN ORGANOBOROXINE.

United States Patent Oflice 3,843,526 Patented Oct. 22, 1974 3,843,526 NOVEL INTUMESCENT COMPOSITION CONTAIN- ING AN AROMATIC AMINE SULFATE Shirley I-I. Roth, Highland Park, and Joseph Green, East Brunswick, N.J., assignors to Cities Service Company, New York, N.Y.

No Drawing. Continuation-impart of abandoned application Ser. No. 99,642, Dec. 18, 1970. This application Apr. 28, 1972, Ser. No. 248,704

Int. Cl. B27k 3/00 US. Cl. 252-81 6 Claims ABSTRACT OF THE DISCLOSURE Boric acid, an organoboric acid, an organoborate, or an organoboroxine is used to improve the char structure of an intumescent aromatic amine sulfate, such as pnitroaniline bisulfate, o-nitroaniline bisulfate, etc.

CROSS-REFERENCE T RELATED APPLICATION This application is a continuation-in-part of copending application S.N. 99,642, filed Dec. 18, 1970, now abandoned.

BACKGROUND OF THE INVENTION Field of the Invention This invention relates to intumescent compositions and more particularly relates to such compositions compr1sing an aromatic amine sulfate as the intumescent agent.

Description of the Prior Art As taught in US. Pat. 3,535,130, certain aromatic amine sulfates are capable of intumescing to form a large volume of carbonaceous char when heated. Unfortunately, the char thus formed is undesirably soft and fluffy and frequently incapable of adhering to a substrate or supporting its own weight. When a char does not adhere to a substrate, it cannot protect it. Thus, these intumescent agents frequently give surprisingly poor flame spread ratings when used.

SUMMARY OF THE INVENTION An object of this invention is to provide a novel intumescent composition.

Another object is to improve the char structure of a foam obtained by the intumescence of an aromatic amine sulfate.

These and other objects are attained by using as an intumescent agent an aromatic amine sulfate in conjunction with a boron compound of the group consisting of boric acid, an organoboric acid, an organoborate, and an organoboroxine.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The aromatic amine sulfate used in the practice of the invention is a sulfate, preferably a bisulfate, of p-nitroaniline, o-nitroaniline, m-nitroaniline, S-amino-l-nitronaphthalene, 4 amino-4-nitrobiphenyl, 1,5-diamino-4,8- dinitronaphthalene, 2 amino-7-nitrofluorene, 4-amino-2- nitrofuran, S-nitroisatoic anhydride, or 4-nitroacetanilide. The preferred aromatic amine sulfates are p-nitroaniline bisulfate and o-nitroaniline bisulfate.

The boron compound is preferably boric acid, but, as indicated above, it may also be an organoboric acid, an organoborate, or an organoboroxine. When it is an organoboron compound, it preferably contains l-6 carbon atoms/organic radical. Exemplary of suitable organoboron compounds are p-bromophenylboric acid, maminophenylboric acid hemisulfate, trimethyl borate, triethyl borate, triethanolamine borate, trimethoxyboroxine,

triisopropylboroxine, etc. The boron compound is used in an amount of about 1-5, preferably about l-3, mols per mol of the aromatic amine sulfate.

For use in protecting a substrate from heat and fire, the intumescent agents of the invention may be applied in any suitable manner, e.g., electrodepositoin, spraying of powdered intumescent agent onto an adhesive substrate, etc. However, it is usually preferred to compound the intumescent agent with a nitrocellulose binder and optionally also with one or more of the other ingredients conventionally used in intumescent compositions, e.g., stabilizers, dispersing agents, pigments, driers, biocides, anti-foamers, thickeners, protective colloids, fillers, blowing agents, etc.; disperse the composition in a suitable liquid medium, e.g., water or a solvent or solvent mixture; and apply the coating composition thus formed to the substrate to be protected, e.g., a wood, paper, metal, or plastics substrate. As is the case with conventional intumescent coating compositions, it is frequently convenient to apply these coating compositions in the form of a paint having a solids content of about 10-70% by weight and an intumescent agent/binder weight ratio of about 0.075-14/1 to deposit a coating having a dry thickness of about 0.001-0.75 inch. Paints wherein the weight of intumescent agent constitutes about 770% of the combined weights of intumescent agent and binder are particularly desirable.

The intumescent agents of the invention intumesce to form an excellent volume of foam having a good, closedcell structure and a density of about 15-10 grams per cubic centimeter. The char has greater rigidity and adherence to substrates than the char formed without the use of a boron compound, and the insulated substrates of the invention have lower heat conductivity.

The following examples are given to illustrate the invention and are not intended as a limitation thereof. Unless otherwise specified, quantitites mentioned are quantitles by weight.

EXAMPLE I Part A-Control Place one gram of p-nitroaniline bisulfate in an aluminum pan and flame it wth a propane torch. The compound intumesces to form an excellent volume of fluffy foam.

Part BControl Place a mixture of one gram of p-nitroaniline bisulfate and one gram of boric acid in an aluminum pan and flame it with a propane torch. The mixture intumesces to form a foam having greater rigidity and about to the volume of the foam of Part A.

Part D I Perform three experiments by repeating Part C except for employing p-nitroaniliue bisulfate/boric acid mol ratios of 1:1, 1:2, and 1:3, respectively. The experiments result in the formation of an enormous volume of fluffy foam, an equally large volume of more rigid foam, and a lesser volume of far more rigid foam, respectively.

EXAMPLE I I Part A-Control Place one gram of o-nitroaniline bisulfate in an aluminum pan and flame it with a propane torch. The compound intumesces to form an excellent volume of very fluffy char.

3 Part B-Control Place one gram of trimethoxyboroxine in. an aluminum pan and flame it with a propane torch. The compound burns with a green flame and forms a white foam wh1ch turns black and collapses.

Part C Place a mixture of one gram of o-nitroaniline bisulfate and one gram of trimethoxyboroxine in an aluminum pan and flame it with a propane torch. The mixture intumesces to form a char having greater rigidity and a somewhat smaller volume than the char of Part A.

EXAMPLE IIICONTROL Dissolve 98.6 parts of a commercial nitrocellulose (69 parts of dry nitrocellulose and 29.6 parts of ethanol) in methyl ethyl ketone. Add (1) additional methyl ethyl ketone to a total of 328 parts, (2) 101.4 parts of ethanol, and (3) 468 parts of p-nitroaniline bisulfate with stirring, and'then incrementally add another 105 parts of methyl ethyl ketone with stirring. Ball mill the mixture for 20 hours to form a coating composition.

Apply two coats of the composition to each of eight preconditioned, primed poplar'panels to form films having a dry thickness of about 0.0180.022 inch, and overcoat four of these coated panels with a nitro-cellulose lacquer. Test the panels in accordance with the two-foot tunnel test described in H. L. Vandersall, The Use of a Small Flame Tunnel for Evaluating Fire Hazard, Journal of Paint Technology, Vol. 39, No. 511, pp. 494-500 (1967).

In each case, the coating intumesces to form a very flufly foam which separates from the panel and, therefore, does not protect it. The overcoated panels have an average flame spread rating of 111 and an insulative value greater than 175 C. (the highest temperature on the scale of the recorder); the other panels have an average flame spread rating of 110.

EXAMPLE IV 7 additional 20 hours.

Prepare and test eight test panels as in Example III. The overcoated panels have an average flame spread rating of 6, an average insulative value of 106 C., and an average degree of intumescence of 41 mm.; the other panels have an average flame spread rating of 9, an average insulative value of 121 C., and an average degree of intumescence of 34 mm.

EXAMPLE V Dissolve 986 parts of the commercial nitrocellulose of Example III in 432 parts of methyl ethyl ketone. Add

101.4 parts or" ethanol, 468 parts of p-nitroaniline bisulfate, and 366.9 parts of boric acid, and continue stirring for an additional 15 minutes. Ball mill the mixture for 20 hours while venting occasionally and incrementally add+ ing a mixture of 58 parts of methyl ethyl ketone and 15 parts of ethanol. Then add a mixture of 64.6 parts of methyl ethyl ketone and 15.7 parts of ethanol, mill for an additional 20 hours, add a mixture of 45.2 parts of methyl ethyl ketone and 11 parts of ethanol, and mill for a final 20 hours.

Prepare and test eight panels as in Example III. The overcoated panels have an average flame spread rating of 0.5, an average insulative value of 122 C., and an average degree of intumescence of 34 mm.; the other panels have an average flame spread rating of --2, an average insulative value of 143 C., and an average degree of intumescence of 32 mm.

It is obvious that many variations may be made in the products and processes set forth above without departing from the spirit and scope of this invention.

What is claimed is:

1. An intumescent composition comprising as the intumescent agent a mixture of (A) one molar proportion of a sulfate of an aromatic amine of the group consisting of p-nitroaniline, o-nitroaniline, m-nitroaniline, 3-

amino-l-nitronaphthalene, 4-amino-4'-nitro-bphenyl, 1,5- diamino 4,8-dinitronaphthalene, 2-amino-7-nitrofluorene, 4-amino-2-nitrofuran, 5-nitroisatoic anhydride, and 4- nitroacetanilide and (B) about 1-5 molar proportions of a boron compound of the group consisting of boric acid, an organoboric acid, an organoborate, and an organoboroxine.

2. The composition of claim 1 wherein the aromatic amine is p-nitroaniline.

3. The composition of claim 1 wherein the aromatic amine is o-nitroaniline.

4. The composition of claim 1 wherein the boron compound is boric acid.

5. The composition of claim 1 comprising the intumescent agent and a nitrocellulose binder.

6. The composition of claim 5 consisting essentially of about 0.075-14 parts by weight of the iilturnescent agent per part by weight of the binder.

References Cited UNITED STATES PATENTS 3,535,130 10/1970 Webb 10615 FP 2,594,937 4/1952 Lauring 106--15 'FP X 3,131,071 4/1964 Hunter 10615 FP 3,371,058 2/1968 Perizzolo 10615 FP X 2,723,212 11/1955 Aarons et al. 10615 FP X 2,948,641 8/1960 McCluer 10615 FP X STEPHEN J. LECHERT, JR. Primary Examiner US. Cl. X.R.

252-378 R, 558; 106l5 PP; 1l7-136, 137 

1. AN INTUMESCENT COMPOSITION COMPRISING AS THE INTUMESCENT AGENT A MIXTURE OF (A) ONE MOLAR PROPORTION OF A SULFATE OF AN AROMATIC AMINE OF THE GROUP CON SISTING OF P-NITROANILINE, O-NITROANILINE, M-NITROANILINE, 3AMINO-1-NITRONAPTHALENE, 4-AMINO-4''-NITRO-BPHENYL, 1,5DIAMINO 4,8-DINITRONAPTHALENE, 2-AMINO-7-NITROFLUORENE, 4-AMINO-2-NITROFURAN, 5-NITROISATOIC ANHYDRIDE, AND 4NITROACETANILIDE AND (B) ABOUT 1-5 MOLAR PROPORTIONS OF A BORON COMPOUND OF THE GROUP CONSISTING OF BORIC ACID, AN ORGANOBORIC ACID, AN ORGANOBORATE, AND AN ORGANOBOROXINE. 